How to measure the coastal currents of Thái Bình?

1. Where is Thái Bình?

Located in northern Việt Nam, Thái Bình is a city of the Red River Delta region. It is formed by a flat and fertile plain crossed by a network of rivers and channels that mark the development of agriculture in the area.

It is historic and culturally wealthy, with a local population attached to the land and water. Handicrafts, vibrant festivals praising the bounty of the land in bountiful harvests, all define the people of Thái Bình-they are large in number, yet so near to the Gulf of Tonkin. The waters along this coast are important both to the local ecosystem and the economy. Relatively shallow water abounds in some of these waters, favorable to increase the abundance of a variety of marine life such as shellfish and small fish. In some places, the coastline is composed of mudflats and mangrove forests, acting very importantly in protecting shores against erosion and as a habitat for numerous species.

2. How is the situation with respect to coastal currents in the area around Thái Bình?

It follows that the coastal currents off Thái Bình will be determined by many combined factors. Tidal forces are among the major influences. Basically, gravitational pull by the moon and the sun causes a rise and fall in sea level, thus causing big tidal currents. These tidal currents, depending on the lunar cycle and particularly depending on the local topography, can show large variations in both speed and direction.

The Red River also plays a part in the development of various coastal currents. It discharges enormous volumes of fresh water into the sea and thus contributes to the establishment of a density-driven current. The river's fresh water is less dense than the sea's saltwater, and the difference in density creates a flow pattern that also acts together with tidal and wind-driven currents.

Weather patterns and winds also play a role. The prevailing winds such as the monsoon winds are able to push the surface waters and hence determine the direction and strength of coastal currents. During the wet monsoon season, winds could bring stronger and more variable currents in contrast with currents developing a more stable pattern during the dry season.

3. How to observe the coastal water flow of Thái Bình?

Characteristics of the coastal currents are pre-determined in the area of Thái Bình by either velocity or flow volume. The velocity can be from low in the immediate vicinity of the shore and within sheltered areas to faster in channels and areas reached by stronger tidal or wind-driven forces. The flow volume depends on the width and depth of the water channel, besides input from the river and tidal exchange.

The measurement of these coastal currents is immensely more sophisticated and effortless with the advent of ADCP current meter, or Acoustic Doppler Current Profilers. They can provide highly accurate and detailed information about flow at various depth levels.

3.1 How does the Doppler principle work in the ADCPs?

Acoustic Doppler Current Profiler(ADCP) is based on the principle of the Doppler effect. They send out sound waves into the water; these pulses of sound, once they hit moving particles in the water-like sediment or small organisms-frequencies of the reflected waves change. The frequency shift is linearly proportional to the velocity of the moving particles and hence to that of the water.

Thus, by transferring several acoustic beams at different angles, ADCP current profiler is able to measure the three-dimensional velocity of the water. Since they are able to find both the horizontal and vertical constituents of the velocity, it becomes possible to fully understand the structure of the flow of water. The derived data thereafter get processed for information that will be useful relating to the coastal currents.

3.2 What's needed for high - quality measurement of Thái Bình coastal currents?

First of all, to achieve high-quality measurement of the coastal currents near Thái Bình, the equipment to be used should contain reliable materials. For this purpose, it has to be resistant to the saltwater corrosion, humidity of the marine atmosphere, and mechanical tension at the time of deployment and operation.

It is also important that the equipment is compact, lightweight, low power-consuming, and cost-effective at the same time for large-scale measurements. The casing of ADCP doppler is preferably made from Titanium alloy. The alloy is highly resistant to corrosion, which is one of the major needs in the salt-water environment near the coast. It is strong and durable, able to stand the physical impacts and pressures. Its relatively low density also contributes to a reduction in the overall weight of the equipment, while it has good thermal stability to support variation in temperature on the sea.

3.3 How to Choose the right equipment for current measurement?

While choosing the equipment for current measurement in Thái Bình, one should pay attention to its deployment method. There exist several types of ADCP flow meter for use in different ways.

If the measurement is to be done from a ship, then a ship-mounted ADCP meter can be applied. It can continuously measure the current as the ship is in motion.

For measurements from the seabed, it can be done by bottom-sitting ADCP. It is placed on the seabed and measures the currents passing above it.

An ADCP profiler on a buoy shall be the appropriate choice in instances when a buoy is used as a floating platform. It is capable of measuring currents around the buoy.

Frequency-wise, a 600kHz ADCP will be good for less than 70m water depth because it gives high-resolution measurement. For water ranging in depths from 70 to 110 meters, a 300kHz ADCP is considered appropriate. For deeper water masses, as great as 1000m, the use of a 75kHz ADCP is recommended because this instrument is capable of deeper penetration in the water mass for effective measurement of currents.

Among the ADCP brands, there are well - known ones like Teledyne RDI, Nortek, and Sontek. However, for a cost - effective option, the China Sonar PandaADCP is a good choice. It is made of all - titanium alloy and offers an excellent price - performance ratio. You can visit https://china-sonar.com/ for more details.

Here is a table with some well known ADCP instrument brands and moels.